Projector keystone correction method, apparatus and system, and readable storage medium

A projector keystone correction apparatus, comprising:

• a first coordinate module which is configured to obtain first coordinate values of a plurality of position points on a projective plane of a projection optical engine by shooting through a Red, Green, Blue-Depth (RGBD) camera in a first coordinate system, wherein the first coordinate system is a space rectangular coordinate system in an optical system of the RGBD camera;
• a second coordinate module which is configured to determine second coordinate values of the position points in a second coordinate system, according to a predetermined conversion relation between the first coordinate system and the second coordinate system, wherein the second coordinate system is a space rectangular coordinate system in an optical system of the projection optical engine;
• a plane fitting module which is configured to perform plane fitting on the second coordinate values of the plurality of position points to obtain a fitted plane;
• and
• a keystone correction module which is configured to perform keystone correction on the projection optical engine according to an included angle between the fitted plane and a coordinate plane of the second coordinate system;
• wherein the apparatus comprises:
• a conversion relation module, configured for predetermining the conversion relation the conversion relation module comprises a projective point unit, a coordinate unit, a correspondence relation unit, and a parameter unit;
• the projective point unit, configured to project an original image with feature points onto a projection screen through the projection optical engine in advance, to obtain projective points of the feature points on the projection screen;
• the coordinate unit, configured to obtain projective point first coordinate values of the projective points by shooting through the RGBD camera in the first coordinate system;
• the correspondence relation unit, configured to determine a correspondence relation between the projective point first coordinate values and feature point coordinate values as (u,v)T=F(R, t, fx, fy, cx, cy)·(x, y, z)T according to a pinhole imaging principle that is satisfied between the projective points and the feature points, as well as the conversion relation that is satisfied between the coordinate values, in the first coordinate system and the second coordinate system, of the projective points, wherein (u,v)T is a column vector of the feature point coordinate values of each feature point in a pixel coordinate system of the projection optical engine, (x, y, z)T is a column vector of the first coordinate values of each projective point, F(R, t, fx, fy, cx, cy) is a function about R, t, fx, fy, cx, cy, R and t are conversion parameters of the conversion relation, fx and fy are respectively a focal length parameter expressed in pixels in an x-axis direction and a focal length parameter expressed in pixels in a y-axis direction of the projection optical engine, and cx and cy are respectively an optical center parameter in the x-axis direction and an optical center parameter in the y-axis direction of the projection optical engine;
• the parameter unit, configured to obtain a parameter R, t, fx, fy, cx, cy according to the correspondence relation as well as multiple sets of the projective point first coordinate values and the feature point coordinate values;
• wherein the apparatus comprises a hardware processor coupled with a memory and configured to execute program components stored on the memory;
• wherein the apparatus comprises a target area module and a keystone correction module;
• the target area module, configured to determine a projection area of the projection optical engine based on the pinhole imaging principle and the plurality of second coordinate values, identify a largest pure-color area or curtain area in a projective plane image captured by the RGBD camera, determine a target projection area of the projection optical engine, and execute the step of performing plane fitting on the second coordinate values of the plurality of position points;
• the keystone correction module, configured to perform keystone correction on the projection optical engine and allow an actual projection area of the projection optical engine to fully fall into the target projection area.